Exhaust manifold of a multi-cylinder internal combustion engine

Abstract

A heat-insulating, light and vibration-proof exhaust manifold for a multi-cylinder internal combustion engine is provided. The exhaust manifold comprises an upper stream flange, a lower stream flange, four manifold pipes at an upper stream, a manifold chamber (gathering section) at a lower stream and a manifold case of a plate metal covering the manifold pipes and the manifold chamber. The manifold pipes have upper stream ends to be connected to exhaust ports of the internal combustion engine through the upper stream flange and lower stream ends gathering in the manifold chamber. Upper stream ends of the manifold pipes and the manifold case are welded to the upper stream flange, and lower stream ends of the manifold chamber and the manifold case are welded to the lower stream flange. The manifold pipe and the manifold chamber can slide relatively at a slide portion which is maintained by pressing the manifold chamber and the manifold case against the manifold pipe.

What is claimed is: 
     
       1. An exhaust manifold of a multi-cylinder internal combustion engine including a plurality of thin wall manifold pipes having upper stream ends connected with exhaust ports of the internal combustion engine and lower stream ends gathering in a gathering section made of a plate metal, comprising: a case of a plate metal fitted around said manifold pipes and said gathering section with a space between;   an upper stream flange to which upper stream ends of said manifold pipes and said case are welded;   a lower stream flange to which lower stream ends of said gathering section and said case are welded; and   a slide portion at which said manifold pipe and said gathering section can slide relatively along a longitudinal direction of said manifold pipe, said slide portion being maintained pressed by said gathering section and said case from exterior.   
     
     
       2. An exhaust manifold as claimed in claim 1, wherein said slide portion is maintained by inwardly projecting parts formed on said gathering section and said case respectively. 
     
     
       3. An exhaust manifold as claimed in claim 1, wherein said slide portion is maintained by meshes arranged between said manifold pipe and said gathering section and between said gathering section and said case. 
     
     
       4. An exhaust manifold of a multi-cylinder internal combustion engine including a plurality of thin wall manifold pipes having upper stream ends connected with exhaust ports of the internal combustion engine and lower stream ends gathering in a gathering section made of a plate metal, comprising: a case fitted around said manifold pipes and said gathering section with a space between;   an upper stream flange to which upper stream ends of said manifold pipes and said case are welded; and   a lower stream flange to which a lower stream end of said case is welded,   lower stream portions of said manifold pipes being welded to upper stream portions of said gathering section, a lower stream end of said gathering section being held so as to slide relatively to said case.   
     
     
       5. An exhaust manifold as claimed in claim 4, wherein at least one of said manifold pipes has an upper stream end or a lower stream portion held so as to slide. 
     
     
       6. An exhaust manifold of a multi-cylinder internal combustion engine including a plurality of thin wall manifold pipes having upper stream ends connected with exhaust ports of the internal combustion engine and lower stream ends gathering in a gathering section made of a plate metal, comprising: a case of a plate metal fitted around said manifold pipes and said gathering section with a space between;   an upper stream flange to which upper stream ends of said manifold pipes and said case are welded;   a lower stream flange to which lower stream ends of said gathering section and said case are welded;   a connecting pipe for connecting said manifold pipe and said gathering section with each other, welded to an upper stream open end of said gathering section; and   a slide portion provided on said connecting pipe by which said manifold pipe and said gathering section can slide relatively.   
     
     
       7. An exhaust manifold of a multi-cylinder internal combustion engine including a plurality of thin wall manifold pipes having upper stream ends connected with exhaust ports of the internal combustion engine and lower stream ends gathering in a gathering section made of a plate metal, wherein a case of a plate metal is fitted around said manifold pipes and said gathering section with a space between, wall thickness of said manifold pipe is thinner than wall thickness of said gathering section, and wall thickness of said gathering section is thinner than wall thickness of said case. 
     
     
       8. An exhaust manifold as claimed in claim 7, wherein a slide portion at which said manifold pipe and said gathering section can slide relatively is provided, and said slide portion is maintained by inwardly projecting parts formed on said gathering section and said case respectively.